As the use of mobile electronic devices, such as PC notebooks, PDAs, cellular telephones, MP3 players, cameras and the like continues to increase, the need for low cost, compact power converters to power and recharge these devices also continues to increase. Most manufacturers of mobile devices typically include plug-in power adapters along with these mobile devices to power and charge batteries of these devices.
Today's power converters are typically AC-to-DC, or DC-to-DC power converters, which are configured to either step-up or step-down the DC voltage input delivered to the mobile device. With AC-to-DC converters, for example, users can power most mobile devices by simply plugging the converter into a standard AC wall outlet commonly found in most homes or offices. Similarly, when only DC input power is available, such as in an automobile or airplane, users can still power their mobile devices by using a standard, off-the-shelf DC-to-DC converter. Normally, both converters are designed and tailored to provide a regulated DC output voltage, which can typically range from between 5 VDC to 30 VDC depending on the kind of mobile device being powered.
Typically, dual output power converters provide power to both the high power output and the low power output and monitor for an over power condition. An over power condition is when the sum total of the output power exceeds a threshold, such as the converter power rating. A typical converter may be rated at 65 W, providing up to 50 W continuous power or more to the main power output, and up to 15 W continuous power to the low power output. When the sum of the output power exceeds the converter 65 W rating for a period of time, the entire converter resets and power is interrupted from both outputs. This complete shutdown is inconvenient to a user trying to utilize or power both devices.
Accordingly, there is a need to avoid a complete shutdown of a dual output converter when an over power condition occurs.
Although these power converters conveniently provide direct power and recharging capabilities, users are often required to carry separate converters to provide power to each individual mobile device. This often means that users have to carry multiple converters: one for an AC input power source, and another for a DC input power source. This often means that users are typically required to carry multiple power converters to power multiple devices. Thus, by carrying multiple mobile devices, users are often forced to carry more than one power supply converter, thereby increasing the amount of bulk a user is required to carry.
Some power converters provide two output voltages enabling two devices to be powered by a single converter. By providing a power converter that has both high power output and low power output terminals, users have the ability to provide power to several mobile devices of varying power requirements, simultaneously, regardless of whether the input voltage is AC or DC.